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Escherichia coli tol-pal mutants form outer membrane vesicles
A Bernadac1, M Gavioli, J C Lazzaroni
1Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UPR 9027, CNRS, Institut de Biologie Structurale et Microbiologie, 13402 Marseille Cedex 20, France.
Journal of Bacteriology
|September 12, 1998
Summary
Mutations in tol-pal genes cause Escherichia coli to release outer membrane vesicles, impacting cell integrity. These vesicles contain essential outer membrane proteins, revealing a new cellular process.
Area of Science:
- Microbiology
- Molecular Biology
- Cell Biology
Background:
- Mutations in tol-pal genes in bacteria lead to altered outer membrane permeability and protein release.
- Other outer membrane defects (tolC, lpp, rfa) also affect permeability.
Purpose of the Study:
- To investigate the role of tol-pal genes in outer membrane structure and vesicle formation.
- To characterize the protein content of vesicles produced by tol-pal mutants.
Main Methods:
- Electron microscopy to visualize outer membrane vesicles.
- Western blot analysis to detect specific proteins in vesicle fractions.
- Plasmid complementation experiments to confirm gene function.
Main Results:
- Strains with mutations in tol-pal genes formed outer membrane vesicles under standard growth conditions.
- Vesicle formation was dependent on tol-pal gene defects, unlike tolC and rfaD mutants.
- Vesicles contained outer membrane trimeric porins and Pal lipoprotein.
Conclusions:
- Defects in tol-pal genes lead to the formation of outer membrane vesicles in Escherichia coli.
- Tol-Pal proteins are crucial for maintaining outer membrane integrity.
- Vesicle formation may be a mechanism to cope with outer membrane defects.